Link, Michael J.

ABSTRACT Background Cerebrospinal fluid (CSF) leak after retrosigmoid vestibular schwannoma resection remains a challenging complication. Historically, surgeons reopened the prior retrosigmoid incision for transmastoid repair because the safety of creating a separate postauricular incision was uncertain, with concerns regarding wound breakdown and infection. However, limited data support this practice, and a focused mastoid incision may offer improved access and patient tolerance. This study evaluated wound healing outcomes following transmastoid repair using a new postauricular incision for persistent CSF leak after retrosigmoid surgery in patients without serviceable hearing. Methods We retrospectively reviewed 27 patients who underwent transmastoid repair for persistent postoperative CSF leak after retrosigmoid craniotomy for vestibular schwannoma (2000–2025). Demographics, operative details, timing of leak diagnosis and repair, wound complications, readmissions, antibiotic use, and culture results were analyzed. Results Median age was 48 years (IQR 41–56); 67% were male, and mean BMI was 29.0 kg/m 2 . Mastoid obliteration was performed in 96%, with fat grafting in 93%. A new postauricular incision was used in all cases. Median time to leak diagnosis was 13 days (IQR 4–79), and median time to repair was 2 days (IQR 1–5). One patient (3.7%) developed a superficial wound abscess; no dehiscence or flap necrosis occurred. At median follow‐up of 34 months (IQR 2.9–87.7), all wounds were healed. CSF leak recurred in two patients (7.4%) and three (11.1%) required reoperation. Conclusion A separate postauricular incision for transmastoid CSF leak repair was not associated with increased wound morbidity. Durable wound healing was achieved in all patients, with 93% legal control, supporting this anatomy‐driven approach. Level of Evidence 4

ABSTRACT Objective Management of vestibular schwannoma (VS) remains controversial. Very small VSs represent a pivotal group: on one hand, they pose the least risk to the patient from the perspective of being small; yet, not recommending treatment may result in missing a critical window for achieving the best outcome. This debate fundamentally hinges on whether treatment improves upon the natural history of the disease. There is an unproven assumption that very small tumors behave similarly to the broader observed population. To address this central question, we conducted a multicenter retrospective review to compare the natural history of tumor growth and hearing for patients with very small VS (1–3 mm) with a referent cohort with larger tumors. Methods All patients diagnosed with sporadic VS 1–3 mm were reviewed at 3 large skull base referral centers and compared with a referent cohort of patients with tumors > 3 mm. Tumor growth‐free survival rates, treatment‐free survival rates, and rates of maintenance of class A, B, or C hearing were estimated using the Kaplan–Meier method. Results In total, 123 patients with very small VS and a referent cohort of 326 patients were studied. Seventeen patients with very small VS experienced tumor growth at a median of 3.2 years after diagnosis (IQR 2.6–5.1), demonstrating a median growth rate of 1.0 mm per year (IQR 0.9–1.8). In comparison, 167 of the patients in the referent cohort experienced tumor growth at a median of 1.7 years after diagnosis (IQR 0.8–3.1). Tumor growth‐free survival rates (95% CI, number still at risk) at 5 years after diagnosis for the 2 cohorts were 84% (75–93, 39) and 45% (40–52, 100), respectively ( p < 0.001). Six patients with very small VS underwent treatment after tumor growth at a median of 3.2 years after diagnosis (IQR 3.2–3.8), compared with 138 patients in the referent cohort at a median of 2.2 years after diagnosis (IQR 1.4–3.6). Treatment‐free survival rates (95% CI, number still at risk) at 5 years after diagnosis for the 2 cohorts were 92% (86–98, 55) and 54% (49–61, 125), respectively ( p < 0.001). Among the 105 patients with very small VS and class A, B, or C hearing at diagnosis, 3 progressed to class D. Comparatively, among the 225 patients in the referent cohort with class A, B, or C hearing at diagnosis, 70 progressed to class D at a median of 2.6 years after diagnosis (IQR 1.0–4.8). Rates of maintenance of class A, B, or C hearing (95% CI, number still at risk) at 5 years after diagnosis were 96% (92–100, 28) for patients with very small VS and 65% (57–73, 70) for the referent cohort ( p < 0.001). Conclusions The natural history of tumor growth and hearing for very small VS diverges favorably from the cumulative natural history data and provides a more appropriate benchmark to compare clinical outcomes of upfront surgery or radiosurgery for this population. At 5 years after diagnosis, 96% of very small VS maintained class A, B, or C hearing and only 8% received treatment for growth within this multicenter cohort. Cumulatively, these data substantiate initial wait‐and‐scan management via size threshold surveillance in this population. Level of Evidence 3.

Objective: To compare disease-specific quality of life (QOL) among patients with sporadic vestibular schwannoma (VS) by tumor management strategy using the recently developed and validated Mayo Clinic VSQOL Index relative to established minimal important difference (MID) thresholds. Study design: Cross-sectional cohort. Setting: Acoustic Neuroma Association and tertiary care center. Patients: Adults with sporadic VS. Interventions: Microsurgery, radiation, or observation. Main outcome measures: VSQOL Index scores were compared by tumor management strategy adjusting for age, sex, setting, tumor size at diagnosis, and duration of follow-up. Scores range from 0 to 100; higher scores indicate better QOL. Results: Of the 652 patients included, 333 (51%) were managed with microsurgery, 175 (27%) with radiation, and 144 (22%) with observation. The mean (SD) duration of follow-up was 6.2 (2.7) years. Global QOL adjusted mean scores (95% CI) differed significantly ( P <0.001) by management group: 70 (67-72) for microsurgery, 73 (70-77) for radiation, and 79 (75-83) for observation. Hearing Problems ( P <0.001), Dizziness and Imbalance ( P <0.001), Problems with Face or Eyes ( P <0.001), and Difficulty with Thinking and Memory ( P =0.03) domain scores also differed significantly by group. Pairwise comparisons that exceeded at least the lower bound of published MIDs included Global QOL scores (microsurgery versus observation) and Hearing Problems scores (microsurgery and radiation versus observation). Conclusions: At a mean follow-up of 6.2 years, several notable statistically and clinically significant differences in QOL were identified. These findings may be used to guide patient counseling regarding management options and require validation in future prospective studies.

OBJECTIVE Communicating hydrocephalus may occur following stereotactic radiosurgery (SRS) for vestibular schwannomas (VSs), yet identifying individual patient risk factors associated with this post-SRS complication remains a challenge. This study examined predictors of nonobstructive ventricular enlargement and symptomatic communicating hydrocephalus following primary SRS treatment for VS via a single-center institutional cohort review and meta-analysis of the literature. METHODS A retrospective single-institution cohort study and systematic literature review and meta-analysis examining post-SRS communicating hydrocephalus in VS was performed. RESULTS The institutional cohort consisted of 634 patients who received primary SRS as treatment for VS. The cohort was 51.6% female, with a median age of 64 (range 18–89) years. Following SRS treatment, 364 patients (57.4%) experienced tumor shrinkage, 218 (34.4%) had no change in the size of their lesion, and 52 (8.2%) experienced tumor growth. Nonobstructive ventricular enlargement was observed in 23 patients (3.6%) following SRS treatment, of whom 9 (39.1%) remained asymptomatic and 14 (60.9%) required placement of a ventriculoperitoneal (VP) shunt, with a median time to shunt placement of 8 months. In the multivariate analysis, patients ≥ 65 years old (p = 0.038), SRS target volume ≥ 5 cm 3 (p < 0.001), maximum SRS dose ≥ 26 Gy (p = 0.015), and tumor growth at the most recent follow-up (p = 0.002) were associated with an increased risk of post-SRS ventricular enlargement. Similarly, patients with older age (p = 0.049), increased SRS target volume (p = 0.002), and tumor growth (p = 0.016) were at an increased risk of symptomatic communicating hydrocephalus requiring VP shunt placement. Twenty-nine studies, including the cohort in this study, met inclusion criteria in the meta-analysis. Of the pooled 7825 patients, the overall incidence of hydrocephalus following SRS was 5%, and a subanalysis of 7081 patients demonstrated the incidence of symptomatic hydrocephalus requiring a VP shunt to be 4%. In this subanalysis, the overall shunting rate in patients who experienced post-SRS ventriculomegaly was 92%. Among individual studies in the literature, increased tumor size was most commonly found to be a statistically significant risk factor for post-SRS hydrocephalus. CONCLUSIONS Approximately 5% of patients may experience nonobstructive ventricular enlargement following primary SRS treatment for VS. However, not all patients may be symptomatic and require shunting. Patients who are older (≥ 65 years), those with larger tumor volumes, and those with post-SRS tumor growth may be at increased risk of communicating hydrocephalus and may benefit from closer clinical monitoring.

Objective: Quality of life (QOL) is an important consideration in vestibular schwannoma (VS) patients when assessing management options. Understanding sex-based differences in QOL may facilitate patient counseling. Study design: Prospective cohort. Setting: Tertiary academic medical center and Acoustic Neuroma Association. Patients: Sporadic VS patients. Interventions: Observation, microsurgery, or radiation. Main outcome measures: Penn Acoustic Neuroma Quality of Life (PANQOL) scores. Results: A total of 481 patients were analyzed. In the observation group, women reported worse anxiety, facial function, and total PANQOL scores at baseline. At follow-up, men declined more in facial function (−5 vs. +3, P =0.01). For microsurgery, women reported worse facial function and balance scores at baseline. At follow-up, men declined more in facial function (−16 vs. −3, P <0.001), balance (−7 vs. +2, P =0.04), energy (−4 vs. +5, P =0.03), and total (−5 vs. +2, P =0.02) PANQOL scores. For radiation, women reported worse anxiety, balance, pain, and total scores at baseline. At follow-up, anxiety improved in women but worsened in men (+5 vs. −6, P =0.008). Sex-based differences exceeding the minimally important difference thresholds established for the PANQOL were observed for the following: anxiety at baseline in the observation group, anxiety and pain at baseline in the radiation group, and change in anxiety from baseline to follow-up in the radiation group. Conclusions: Women had worse anxiety, balance, facial function, pain, and overall QOL at baseline assessed using the PANQOL, whereas men declined more with treatment and observation. The largest difference in PANQOL change between sexes occurred after microsurgery, with men experiencing greater losses in facial function, balance, energy, and total scores.

BACKGROUND AND OBJECTIVES: Contemporary skull base surgeons must understand transcranial and endoscopic endonasal approaches to the petrous apex (PA). We provide an anatomic overview and comparison of main approaches to the PA through illustrative anatomic dissections. METHODS: On 10 sides of 5 specimens, transcranial approaches to the PA including the anterior petrosal, transcochlear, and retrosigmoid with suprameatal extension were performed. For endoscopic endonasal approaches, the transclival approach was performed in the midline of 5 specimens and its contralateral transmaxillary extension was performed on 10 sides. RESULTS: The anterior petrosal approach offers an anterolateral view of the PA bounded by petrous ridge posteromedially, internal auditory canal posterolaterally, greater superficial petrosal nerve anterolaterally, and lateral boundary of cranial nerve V, the Gasserian ganglion, and V3 anteromedially; it exposes the middle fossa and, once the PA is removed, the superomedial cerebellopontine angle. The transcochlear approach affords a lateral view of the PA defined medially and inferiorly by inferior petrosal sinus, posteriorly by posterior fossa dura, anteriorly by the petrous internal carotid artery, and superiorly by the superior petrosal sinus and middle fossa dura. Through a retrosigmoid approach, the PA is bounded by the superior petrosal sinus superiorly, the sagittal plane of cranial nerve VI medially, and the axial and sagittal plane of the internal auditory canal porus inferiorly and laterally, respectively. It affords a panoramic view of the posterior fossa and access to Meckel's cave after PA drilling. Endoscopic endonasal approaches target the anteromedial PA, and it is demarcated by a triangle consisting of cranial nerve VI posterolaterally, the paraclival segment of the internal carotid artery anteriorly, and the petroclival synchondrosis inferiorly and medially. The addition of the contralateral transmaxillary approach enhances lateral access up to the internal auditory canal. CONCLUSION: We provide a comprehensive overview of the main approaches to the PA through illustrative anatomic dissections and representative cases.

Objective: To examine microsurgical outcomes of medial sporadic vestibular schwannoma (VS), defined as a spherical tumor within the cerebellopontine angle (CPA) without tubular internal auditory canal (IAC) extension, compared with a referent cohort of “typical” VS with IAC extension. Study design: Historical matched cohort study. Setting: Tertiary referral center. Patients: Forty patients with medial sporadic VS who met the inclusion criteria were each matched to 3 referent patients by age, CPA tumor size, preoperative hearing class, and surgical approach. Interventions: Microsurgical resection. Main outcome measures: Extent of resection, immediate and long-term postoperative facial nerve weakness (House-Brackmann grade >I), and long-term hearing preservation were compared between patients with medial VS and the referent cohort using conditional logistic regression. Results: Medial VS and matched patients with IAC extension were not statistically significantly different in nongross total extent of resection (OR: 1.04, 95% CI: 0.47-2.31), immediate (OR: 0.82, 95% CI: 0.40-1.67) or long-term (OR: 0.59, 95% CI: 0.23-1.48) postoperative facial nerve weakness, or long-term nonserviceable hearing (OR: 0.84, 95% CI: 0.17-4.22). Conclusions: In this matched cohort study of medial VS, we found no statistically significant differences in the extent of resection, facial nerve function, or hearing preservation between tumors with and without IAC extension.

Objective: To evaluate hearing outcomes after treatment with stereotactic radiosurgery (SRS) for sporadic vestibular schwannoma (VS) among patients with baseline 100% word recognition scores (WRS). Study design: Historical cohort. Setting: Tertiary academic medical center. Patients: Patients with 100% WRS on audiometric testing at initial treatment with SRS. Interventions: Gamma Knife SRS. Main outcome measures: Rate of maintaining serviceable hearing (SH), defined as American Academy of Otolaryngology-Head and Neck Surgery hearing class A or B. Results: In total, 125 patients had 100% WRS at SRS for sporadic VS. Median age at SRS was 56 years (IQR: 51 to 62) and median pure tone average (PTA) at SRS was 20 dB HL (IQR: 13 to 31). Sixty-eight patients progressed to non-SH at a median of 3.4 years after SRS (IQR: 1.0 to 8.6); the median duration of follow-up for the 57 patients who maintained SH was 5.1 years (IQR: 2.8 to 9.6). Rates of maintaining SH (95% CI, number still at risk) at 1, 3, 5, 7, and 10 years after SRS were 88% (82 to 94, 101), 75% (68 to 84, 81), 61% (53 to 71, 55), 58% (49 to 68, 43), and 44% (35 to 56, 26), respectively. Each 10-dB HL increase in PTA at SRS was associated with a 52% increased risk of progression to non-SH (hazard ratio: 1.52, 95% CI: 1.24-1.87, P <0.001). Conclusions: Despite having 100% pretreatment WRS, most patients with sporadic VS treated with SRS experienced clinically significant hearing decline over time. Even among this cohort of patients with excellent baseline hearing, at 10 years after treatment, only 44% of patients maintained SH.